In order to ensure the stability, reliability and dynamic balance for a color wheel, an effective dynamic balance method and optimal structure in the manufacture process are very important. There are several methods which have been introduced in several US patents. While in dispensing the glue for bonding a color filter set on the bonding area, due to viscous flow of the glue before drying, the thickness of the glue may be coated unevenly, which would cause the color wheel to not run in perfect dynamic balance status.
Furthermore, once the glue is in excess, it may overflow and stain the filter set. When a color wheel is running at high speed and at high temperature, the centrifugal force keeps acting on the balancing material, which would cause the balancing material to decompose, deviate and finally to be lost from the color wheel. On the other hand, to prevent excess glue overflow and staining of the filter, and to lower the chance of which the balancing material deviating from the color wheel in high speed high temperature operation, U.S. Pat. No. 6,705,733 provides a color wheel structure, featuring a groove which has narrow inside and wider opening on the metal ring of the color wheel for receiving the excess glue while adhering the filter set onto the metal ring. The shape of the groove suggested by patent '733 is totally contrary to the dovetailed balancing groove of the present invention. U.S. Pat. No. 6,618,214 suggests a color wheel structure, featuring a plurality of grooves on the bonding surface of a metal ring for receiving the excess glue to prevent overflowing which may stain the filter. U.S. Pat. No. 6,598,977 provides a color wheel structure, featuring several through holes on the bonding surface of the metal ring, using the holes to let excess glue be sucked from the back of the bonding surface, thus to prevent excess glue overflow and detain the filter set, and to keep the glue coated evenly.
All the patents stated above have a groove on the metal ring for loading the balancing material and solving the problems which are caused by the excess glue or adhesive. However, all the prior art did not consider how to use the shape of the groove to help the balancing material sustain stronger centrifugal force so as not to deviate from the color wheel. The prior art also has no teaching about the design and use of the function of dovetailed balancing groove with narrow opening. However it is the main point of the present invention to use the design of the groove to overcome the problems stated above.